1. Field of the Invention
The present invention relates to a network-connected information processing apparatus having a power saving mode and an information processing method and a computer program product for the information processing apparatus.
2. Description of the Related Art
Recently, such a network system that a plurality of information processing apparatuses, such as a computer and a printer, is connected to one another by, for example, an Ethernet (Registered Trademark) local area network (LAN) connection thereby enabling data transmission/reception among the information processing apparatuses has been in widespread use. The information processing apparatus typically has a power saving mode in which power supplying to part of the apparatus is temporarily shut off by a control unit including a central processing unit (CPU), thereby reducing power consumption, which is disclosed, for example, in Japanese Patent Application Laid-open No. 2003-191570.
A technology disclosed in Japanese Patent Application Laid-open No. 2003-191570 is such that when an apparatus receives a packet via a network after switching to the power saving mode by the control of a CPU, if the packet does not need to be processed, the packet is discarded by a filter while keeping the power saving mode thereby keeping a low power consumption state for a long time. However, in the above technology, the apparatus performs the power saving control while always keeping the CPU and the like in a normal power mode, so that power is consumed by the CPU and the like even in the power saving mode. Therefore, it is difficult to effectively reduce power consumption.
To address the above problem, for example, an apparatus disclosed in Japanese Patent Application Laid-open No. 2000-141821 is known. This apparatus is switched to the power saving mode by shutting off power supplying to each unit in the apparatus such as a data processing unit and a control unit including a CPU, and includes a unit that, when the apparatus in the power saving mode receives an apparatus-state obtaining request from an external network device, responds to the request while keeping the power saving mode.
However, in the technology disclosed in Japanese Patent Application Laid-open No. 2000-141821, every time the apparatus receives data such as a packet other than the apparatus-state obtaining request, the data needs to be processed by the CPU, and therefore the CPU and the like need to be switched to the normal power mode. Therefore, the apparatus cannot keep the CPU and the like in the low power consumption state for a long time, thus may not be able to obtain sufficient effect of lowering power consumption.
Moreover, in each of the above-described technologies, when the CPU of the data processing unit processes data received via a network, the CPU performs the processing while always keeping the normal power mode regardless of a type of the received data or the like. Therefore, the technologies have a problem in that power is consumed uselessly in some data processing depending upon a type of received data or the like (e.g., a packet that is processed easily by the CPU and a packet for a protocol that does not require fast processing time and response time). Accordingly, in the apparatuses of the above-described technologies, data processing cannot be performed in a power state appropriate for each data, and received data is always processed by the data processing unit in a specific power mode. Thus, power consumption of the apparatus may become large, leading to the need of further reducing power consumption.